(a) Field of the Invention
The present invention relates to a method and apparatus for filtering pixel blocks, and more particularly, to a method and apparatus for filtering pixel blocks which can efficiently process pixel blocks adjacent to partition boundaries in parallel when segmenting an image frame and processing it in parallel.
(b) Description of the Related Art
HEVC (High Efficiency Video Coding) is a video standard that is currently being established by the JCT-VC (Joint Collaborative Team on Video Coding) jointly organized by ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11. HEVC uses picture partitioning schemes for the purpose of video parallel processing or for the purpose of improving robustness to errors occurring during transmission.
The picture partitioning schemes for HEVC largely include slices, tiles, and WPP (wavefront parallel processing). These picture partitioning schemes are also expected to be widely used in other video standards as well as HEVC. Even if the video standard does not explicitly support picture partitioning, methods of partitioning a picture for parallel processing are used depending on the method of video codec implementation.
Meanwhile, in order to reduce image quality degradation due to blocking artifacts produced when grouping pixels included in an image into blocks and processing the blocks, most video standards use their own filtering method for restored signals. A typical example of this filtering method may include deblocking filtering, which is an in-loop filtering method employed by H.264/AVC, HEV, etc. Deblocking filtering of a pixel block involves data dependency on pixels in neighboring blocks. In some cases, other filtering methods than deblocking filtering may be additionally used to reduce image quality degradation among pixel blocks or within pixel blocks. They also involve data dependency among neighboring pixel blocks.
Even when splitting a picture into a number of picture partitions by the aforementioned picture partitioning method and allocating the picture partitions to processing elements for independent processing, pixel blocks adjacent to picture partition boundaries need to be filtered. When the pixel blocks adjacent to picture partition boundaries is filtered by an additional processing elements, cost for the additional processing elements is occurred.
Alternatively, a processing element allocated to a picture partition may be put into standby until pixel blocks in neighboring picture partitions are processed for filtering picture partition boundaries, which results in degradation in video processing speed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.